Protocols for three-dimensional molecular imaging using mass spectrometry

Andreas Wucher, Juan Cheng, Nicholas Winograd

Research output: Contribution to journalArticlepeer-review

93 Scopus citations

Abstract

A protocol for three-dimensional molecular thin-film analysis is described that utilizes imaging time-of-flight secondary ion mass spectrometry and large-area atomic force microscopy. As a test study, a 300-nm trehalose film deposited on a Si substrate was structured by bombardment with a focused 15-keV Ga+ ion beam and analyzed using a 40-keV C60+ cluster ion beam. A three-dimensional sputter depth profile was acquired as a series of high-resolution lateral SIMS images with intermittent erosion cycles. As the most important result of this study, we find that the structured film exhibits a highly nonuniform erosion rate, thus preventing a simple conversion of primary ion fluence into eroded depth. Instead, the depth scale calibration must be performed individually on each pixel of the imaged area. The resulting laterally resolved depth profiles are discussed in terms of the chemical damage induced by the Ga+ bombardment along with the physics of the C 60+ induced erosion process.

Original languageEnglish (US)
Pages (from-to)5529-5539
Number of pages11
JournalAnalytical Chemistry
Volume79
Issue number15
DOIs
StatePublished - Aug 1 2007

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry

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